Prescribed burning in Italy: issues, advances and challenges
iForest - Biogeosciences and Forestry, Volume 6, Issue 2, Pages 79-89 (2013)
doi: https://doi.org/10.3832/ifor0803-006
Published: Feb 07, 2013 - Copyright © 2013 SISEF
Review Papers
Abstract
Prescribed burning has been carried out since the late 1970s in several southern European countries. Italy hosted some pioneer experiences in the early ’80s, but these did not follow up into practical implementation, and few studies and applications were carried out in subsequent years. In the last decade, a new interest arose and several experiences were carried out. We aim to illustrate the limitations, advances and challenges of prescribed burning in Italy by reviewing the national literature of the last 40 years on this subject. Unfavorable land characteristics, conflicting management goals, a hostile socio-cultural environment, and an inadequate regulatory framework have supposedly limited the application of prescribed burning in Italy. Nevertheless, in the last 20 years the legislation at the regional level has been updated to consider the use of fire, and new procedures to authorize prescribed fires allowed for experiments and application, even within National Parks. From 2005 to 2012, prescribed burning programs for fire hazard reduction, forest and range management, biodiversity conservation and firefighter training were implemented throughout Italy. Several vegetation and fuel types were involved (e.g., broadleaved and coniferous forests, Mediterranean and continental shrubland, grassland, slash). Studies on fire behavior and effects helped to set prescriptions for specific objectives and environments. Results were transferred to professionals through training sessions. Some of the challenges ahead are improving the legislative framework, e.g., by introducing a certification for the use of fire, and addressing issues of pastoral fire through conflict resolution programs. Prescribed burning in Italy could be developed by committing to carry out ecological studies on its implications to silviculture, range management and habitat conservation.
Keywords
Wildfire, Integrated Fire Management, Biodiversity, Historical Fire Use
Introduction
Prescribed burning (PB) has been used worldwide since the first half of the 20th century for fire hazard reduction, forest and range management and biodiversity conservation ([63]). In Europe, the planned use of fire has a long history of application, e.g., in heathland management in the Atlantic area ([24]), understory burning in southern Europe ([44]), forest regeneration in Scandinavia ([36]). However, PB as a professional land management technique (i.e., having clear prescriptions and evaluation protocols) developed at the end of 1970s ([77]). In central and northern Europe, PB is used mainly for conservation and forest regeneration purposes. It is applied extensi- vely in the United Kingdom ([24]), Sweden (over 4000 ha yr-1 - [36]), Finland (2000 ha yr-1 - [87]), Germany (750 ha yr-1 - Held A., personal communication), while in other countries it has experimental application ([44]). In the Mediterranean area, PB programs were designed in the 80s-90s for fire hazard reduction in France, Portugal and Spain, leading to an increase in trained personnel ([77]). Burnt area is currently around 5000 ha per year in France, 2000 ha in Portugal and 1000 ha in Spain, and the use of PB has been extended to habitat conservation, grazing, game and forest management ([44]).
In Italy, interest in PB rose in the late 70s ([81]), about at the same time than in other European countries. Calabri ([16]), chief of the Fire Service of the National Forest Service, acknowledged the potential use of PB to rationalize the use of fire in range management, prevent pastoral fires from originating wildfire, and improve rangeland productivity. He acknowledged the applicability of PB for fire hazard reduction and tree regeneration in Mediterranean pine forests and for fuel break management, and its potential value in firefighter training. Experimental PB in Mediterranean pine forests (Tuscany) and for fuel break management (Sardinia) followed in the 80s under the supervision of Istituto Sperimentale di Selvicoltura ([15], [17]). Despite “promising” results ([17]), the outcomes were not monitored in the following years, nor implemented in ordinary forest management. Unlike France, Portugal and Spain, where experiments were followed by investments in research, application and training ([77]), interest in PB in Italy died off. Only one experiment is documented in the 90s, aimed at fuel break management in Sardinia ([51]). In the last 10 years, however, PB regained attention. Seminars, training courses and scientific experiments were carried out in cooperation with firefighting organizations, local administrators, universities and professionals from several regions ([7]).
This work aims to: (i) ascertain the reasons for a limited or delayed development of PB in Italy, in comparison with other European (particularly Mediterranean) countries; (ii) summarize goals, methods and results of PB activities carried out in Italy during the last 10 years; (iii) point out open research questions to be addressed for the future development of PB in the country.
Issues of prescribed burning in Italy
Several authors evidenced potential limitations to the application of PB in Italy ([80], [16], [15], [17], [79], [45]). These can be due to unfavorable land characteristics, conflicting management goals, hostile socio-cultural environment, or inadequate legislation (Tab. 1).
Tab. 1 - Limitations to the use of prescribed burning in Italy according to several Italian authors.
Limitations | Description |
---|---|
Land characteristics | Extent of rural-urban interface; forests, shrublands and rangelands in mountain territories; vegetation constituted by fire sensitive species; extent and fragmentation of the private property. |
Management policies | Priority investments in fire control policies; preference towards forest expansion and rangeland reduction; preference for ecological successions towards late-successional and less flammable forests; silviculture mainly focused on natural tree regeneration. |
Cultural | Fear of fire; lost of expertise in traditional fire uses by the rural population; surreptitious use of fire in agricultural and pastoral systems; public opinion mainly accustomed to fire control policies; poor knowledge of ecological effects related to fire. |
Legislation | Absence of a national legislative framework; high heterogeneity of the legislation at the regional level; confusion between prescribed burning and other fire uses; lack of clear authorization processes and definition of liability; lack of certification programs. |
Land characteristics
Forest species traits, and an overdeveloped rural-urban interface (RUI), are the main ecological and geographic issues that could have been limiting the use of PB in Italy ([80], [16], [45]). Fire-adapted forest types where PB is commonly applied in southern Europe (conifers: Pinus canariensis Smith, P. halepensis Mill., P. laricio Poiret., P. pinaster Ait., P. pinea L.; broadleaves: Eucalyptus sp., Quercus sp.) are sporadic in Italy, i.e., 7% of total forest cover by conifers, 19.1% of which has an uneven-aged structure, and 13% by broadleaves (Tab. 2 - [40]). On the other hand, shrub communities usually targeted by PB (i.e., heathlands, Mediterranean scrublands) represent 70% of shrub-type formations in the country ([40]). However, Susmel ([80]), a leading Italian ecologist of the 20th century, maintained that PB could accelerate the degradation of Mediterranean scrublands that had been repeatedly burnt by wildfire between the 50s and the 70s. In a national survey on the awareness and perception of fire by professional foresters ([45]), 72% of the interviewees answered that potential damage to vegetation was the main limit to PB implementation in the field.
Tab. 2 - Land and wildfire characteristics of Italy and of south European countries where prescribed burning is used. (1): Forest data have been derived from National Forest Inventories published on respective web sites (Italy: Inventario Nazionale delle Foreste e dei Serbatoi Forestali di Carbonio - ⇒ http://www.sian.it/inventarioforestale/; France: Inventaire Forestal Nacional - ⇒ http://www.ifn.fr/spip/; Portugal: Inventário Florestal Nacional - ⇒ http://www.icnf.pt/florestas/ifn/; Spain: Inventario Forestal Nacional - ⇒ http://www.magrama.gob.es/es/biodiversidad/temas/inventarios-nacionales/inventario-forestal-nacional/); (2): Statistics for the French territory have been calculated only for southern Departments where prescribed burning is implemented on a broad scale: Provence-Alpes-Cote-d’Azur, Corse, Languedoc-Rousillon, Midi-Pyrénnées, Aquitaine; (3) From respective National Forest Fires Inventories and [73]; (4) Data from [21].
Land characteristics (1) | Italy | France (2) | Portugal | Spain |
---|---|---|---|---|
Land area (km2) | 301 336 | 154 113 | 92 391 | 505 957 |
Population density (pers./km2) | 202 | 90 | 115 | 89 |
Road density (km/ km2) | 1.50 | 1.77 | 0.87 | 1.32 |
Forest area (ha) Private Property (%) |
8 705 220 66% |
8 182 000 80% |
3 458 556 93% |
18 571 403 70% |
Shrub/grassland area (ha) Private Property (%) |
4 432 910 (shrub) 15% |
1 907 000 89% |
1 926 630 88% |
25 141 335 n.a. |
% of vegetation land cover | 44 | 65 | 58 | 86 |
% forests at elevation 0-500 m | 34 | 53 | 87 | n.a. |
% forests at 500-1000 m | 38 | 28 | 12 | n.a. |
% forests > 1000 m | 28 | 18 | 1 | n.a. |
% forests with slope > 60% | 29 | 22 | n.a. | n.a. |
Conifer sp. where prescribed fire is used in South Europe (% tot. private forest) |
7 50% |
18 90% |
29 86% |
53 n.a. |
Broadleaf sp. where prescribed fire is used in South Europe (% tot. private forest) |
23 85% |
24 93% |
26 96% |
15 n.a. |
Wildfire characeristics (3) | ||||
Average burnt area (ha yr-1; 1980-2010) Burnt forest (% total burnt area) |
118 085 41% |
20 332 n.a. |
113 033 53% |
178 941 38% |
% tot. vegetation area burnt yearly (%) | 1.29 | 0.20 | 2.10 | 0.41 |
Intentional fires (% total) (4) | 80 | 21 | 38 | 68 |
Calabri ([17]) highlighted that PB can be problematic in complex topographies and highly variable wind patterns. Some 66% of Italian forests is located at elevations > 500 m, and one third on slopes > 60% (Tab. 2 - [40]). However, this issue is not controversial in other countries such as Portugal (where PB is carried out on slopes of 0-68% and elevations of 150 to 1000 m a.s.l. - [30]) or France, where PB is applied in sites that are morphologically similar ([43]) or equivalent ([10]) to the Italian mountains.
Another issue, shared by all southern European countries, is the preponderance of private ownership and real estate fragmentation in forests ([16] - Tab. 2). However, this is relevant also in other Mediterranean countries where it has been addressed by involving landowners in PB-related decisions according to a participatory approach to land planning, as illustrated below (e.g., [10], [43], [88]).
Finally, it has been suggested that PB in presence of an overdeveloped RUI could be detrimental to health and safety in urban areas (e.g., air quality, road visibility - [17]). Population has been rising steadily in Italy since the late 80s, and population and road density are currently among the highest in southern Europe (Tab. 2). Following depopulation in mountain areas (62 inhabitants km-2, on average), human pressure has increased in the lowlands and coastal regions ([28], [23]). This issue is complex, and shared by other southern European countries ([44]). For example, in the Alpes-Maritimes (southern France) population density is comparable to Italy (250 inhabitants km-2), and particularly high along the coasts (888 inhabitants km-2). Here, PB covers ~1600 ha yr-1 and is mainly used for fire hazard reduction, also at the rural-urban interface. Strong efforts have been sustained in order to mitigate smoke-related issues, mainly by developing suitable fire prescriptions and implementing conflict resolution strategies ([10]).
Land management goals
The adequacy of PB depends on the management goals being prioritized ([80], [16], [79]). Universal acknowledgment is given to the wildfire issue, which is the main cause of damage to Italian forests ([40]), and has been occurring in several catastrophic fire seasons in the last 30 years ([73]). The ratio of the yearly burnt area to total vegetation cover in Italy is second only to Portugal (Tab. 2). Nevertheless, investing in PB as a preventive measure was considered to be conflicting with other land management policies ([80], [79], [17]).
In the wake of a widespread debate on the profitability of range vs. forestry systems ([79]), Susmel ([80]) suggested that periodic wildfires in Mediterranean areas in the 60s-70s, caused mostly by shepherds and criminal action by real estate constructors, were the main reason for hydrogeological hazard, loss of plant diversity and lack of adult stages in shrubland communities. Consequently, he recommended reducing fire frequency by a fire suppression strategy to promote late-successional, “climacic” forests (e.g., Quercus spp.) that could produce higher timber and landscape values, and have a lower flammability.
In Italy, the history of fire management has been dominated by fire control polices, often at the expense of investments in silvicultural prevention ([13]). In several countries outside Europe, the transition from fire control to fire management policies, which include PB, occurred as a result of catastrophic fires that caused much distress in firefighting systems ([54], [41], [63]). Likewise, PB in southern Europe received a boost after large fires in summer 2003 and 2005, when a novel fire management approach, integrating wildfires within prescription, the planned application of fire, and traditional fire uses (e.g., pastoral burning) to meet the overall objectives of land management, was developed ([77]). In Italy, however, critical seasons such as the summer of 2007 (227 729 ha burnt, the worst season of the last 30 years - [73]) have not lead to significant investments in land planning and fuel management ([27]). Rather, fire suppression policies have been progressively enforced by significant amounts of public financial resources ([34]). In other words, wildfires have been dealt with more as a civil protection emergency than as a land management issue ([13]). Opinion was that the costs of extinction could be backed up by public interests such as employment opportunities, political convenience, industry business or commerce. Measures of preventive silviculture such as PB were more difficult to implement, and could not find a comparable economic justification ([17]).
Another concern has been that forest management in Italy is aimed primarily at promoting natural regeneration and uneven-aged stand structures, that were considered incompatible with the use of fire in the forest ([80], [16], [79]). Forest management systems adopted in other countries, especially in even-aged conifer stands where PB is applied, are based on artificial regeneration. Afforestation has been carried out in many southern European countries in the 20th century ([58]), including Italy, where 40% of even-aged conifer forests are planted ([40]). However, plantations have not been managed for production purposes ([85]), nor followed arboricultural planning methods such as those applied, e.g., in Portugal ([30]). Since the main goal of Italian plantations was to facilitate the establishment of native hardwoods, PB was feared to alter the desired succession dynamics ([16]). In regard to industrial plantations, in Italy these are only 1.4% of total forest cover ([40]), and only 25% of these includes tree species commonly subject to PB in European countries. In addition, unlike those in other countries (e.g., [31]), only 18.4% of Italian private industrial plantations belongs to large companies, firms and industries ([40]); the interest of small landowners in financing measures of preventive silviculture is much more limited.
Socio-cultural issues
The fear of fire is one of the greatest limits to PB in Italy ([17]). Professionals are afraid to lose control of the flame front ([45]). Susmel ([80]) argues that centuries of detrimental fire use, especially by shepherds, have contributed to exacerbate the public perception of fire and fire use. In particular, after a long history of fire use, the socio-economic changes that occurred in rural areas at the end of the 16th century changed the way fire was being used in agriculture and livestock breeding, and have been affecting negatively its social acceptance ([16], [26], [22]).
Fire has long been used for agro-silvo-pastoral purposes in Italy ([76]). In the Greco-Roman world, the use of fire was widespread in Mediterranean Italy ([80]) to create or regenerate pastures, fertilize fields, hunt, and control pests ([76], [62]). Also in the Alps, between 6500 BC and 800 AD, slash and burn (debbio) was broadly used to open new pastures and agricultural fields ([1], [82], [18], [29]). However, starting from the late Middle Ages, the use of fire in northern Italy decreased ([22]). Pyne ([63]), describing fire uses in central Europe, reports that in the 16th century the conversion of most forest areas into agricultural land and pastures made the use of fire less necessary. Population growth and the development of cities built with flammable materials demanded greater control of fires in RUI areas. In the 19th century, the shortage of timber resources, forests privatization, and the development of timber industry ([61]) required increased fire control and the prohibition of agro-pastoral use of fire ([62]). Similar dynamics occurred north and south of the Alps, so that in the last three centuries the use of fire has been increasingly limited and confined to the mere management of marginal agricultural and pastoral areas ([3], [22]).
In the lowlands, fire has been used until recently to regenerate reed stands of Phragmites australis (Cav.) Trin., whose sprouts were used for roofing ([64]). Fire is still used to remove the stubble in rice fields but must comply with special regulations ([14]). In forests, fire has been used until the II World War to remove the understory in chestnut orchards ([17]). In rangelands, fire has been a common practice to control shrub and tree encroachment until the beginning of the 20th century ([22]), e.g., by eliminating Swiss stone pine in low-density, grazed larch forests ([1], [74]). Fire scars on old larch trees (Fig. 1) preserve the memory of this practice ([38]). The use of fire in these areas has declined in the last century, due to the decrease of livestock units and the improvement in farming methods. However, shepherds throughout the Alps still practice it occasionally ([22]). This habit is controversial: on one hand, burning helps maintaining the pastures, on the other it is now applied surreptitiously in high fire danger seasons resulting in unclear effects on the ecosystem and ultimately higher costs for fire control systems ([3]). These issues are common in central and southern Italy ([26]), where the fire is widely used to remove stubble and regenerate pastures (Fig. 2). Irresponsible or illegal use of fire is a major cause of wildfire in southern Italy ([17], [53], [49]). Among southern European countries, Italy has the highest percentage of unintended fire ignitions ([21]), accounting for nearly 80% of the causes (Tab. 2). It is commonly thought that most ignitions are criminal ([47]). However, this belief leads to underestimate the issues of poorly regulated use of fire for agricultural and pastoral purposes ([49], [65]). An example is provided by the 2007 fire season: 43.2% of unintentional ignitions were attributed to negligence in stubble burning, while pastoral fires were behind 31.1% of intentional ignitions - or probably more, since 56.6% of them had an unknown cause ([72]). The uncertainty on causes of wildfire fuels public alarm ([49]), so that the use of fire is now a cultural taboo among professionals ([26]), who also share a lack of knowledge on the ecological effects of fire, and of PB in particular ([45]).
Fig. 1 - Multiple fire scars on a larch trunk. In grazed larch forests of the Alpine region it is common to observed old larch individuals with overlapped fire scars at the trunk base indicating recurrent fires due to pastoral burn practices to maintain open forests.
Fig. 2 - Field and pasture burning in Sicily. In southern Italy fire is commonly used to eliminate the vegetation along roads, around houses and in open fields. Fire is applied surreptitiously and rarely people managing the burn can be observed, resulting in uncontrolled fires which spread out of the area intended to be burnt.
Legislation
In Italy, forests are subjected to land use restrictions, e.g., for hydrogeological protection (87.1% of forest land) or landscape conservation (100%). Management actions must be authorized and comply with regulations and forest management plans. The longest standing of such regulations, i.e., RDL 3267/ 1923 on soil conservation, categorically banned the use of fire from forests ([17]).
PB was rarely mentioned in national regulations concerning either wildfire or silviculture ([17], [45]). The first national law for wildfire protection (e.g., L. 47/1975) left the matter of PB unregulated. Similarly, regional laws that authorized PB were initially issued in only a few regions of Italy ([15]). While France and Portugal introduced PB in their national laws in year 2001 and 2004, respectively ([44]), in Italy the second national law on wildfire (L. 353/2000) failed to address the matter ([14]). Calabri ([16]) and Leone et al. ([45]) argued that the absence of clear guidelines in PB regulations, especially concerning the attribution of responsibilities in the use of fire, has de facto prevented its implementation even when the interest was there. Field experimentation, which could have provided a better understanding of fire behavior and effects in Italian ecosystems (e.g., [35], [12], [68]), have been limited for similar reasons ([52]).
Advances in prescribed burning in Italy
Despite the aforementioned issues, most authors have insisted on the need to update the legislation and set up long-term multidisciplinary studies to test PB for different objectives in representative ecosystems of Italy ([80], [16], [15], [79], [51], [45], [75]). However, in the recent years the regulations changed ([14]). Different regions updated their legislation on wildfire, forest management and fire control planning (Fig. 3), introducing the possibility to authorize experiments and applications of PB ([25], [46], [83], [55]). Since 2009, PB can be authorized even within Regional Parks ([7]), National Parks and State Reserves, and today 6 out of 24 National Parks include PB in their Fire Management Plans (Fig. 3).
Fig. 3 - The regulatory framework in Italy. Italian Administrative Regions in which prescribed burning has been experimented (light grey), and regional legal framework regulating prescribed burning (updated at 2012): Regional Law in Forest and Fire Management (black circles); Regional Fire Management Plans (crossed grey circle); Fire management Plan of National Parks (white quadrate); Fire and Forest Prescriptions (grey triangle).
A review of 236 normative documents dealing with fire and forests ([14]) evidenced that PB is currently addressed in 14 Italian Regions, albeit with a remarkable heterogeneity in terminology, objectives and administration. The use of fire for wildfire hazard reduction is acknowledged by all Regions (100% of the documents), and is prescribed for the reduction of litter in coniferous forests, especially in Mediterranean areas, and for fuel management in shrubby and herbaceous firebreaks ([14]). Other objectives, such as range management, habitat conservation are less represented (Fig. 4a); the use of fire for silvicultural purposes is mentioned only once. The PB authorization process is regulated in 60% of the cases, but its planning (e.g., prescriptions) and the attribution of responsibilities are neglected in most of the texts (Fig. 4b).
Fig. 4 - Percentage of legislative documents regulating prescribed burning in Italy (n. 34 out of 236 analyzed) by management goal (a) and contents in the text (b). Modified from Bovio & Ascoli ([14]). Data are updated to 2012.
The updated legislation, despite some limitations, has set the scene for PB experiments in many Regions (Fig. 3). Research on PB and knowledge transfer from science to practitioners have been encouraged by the active partnership of Firefighting Departments, administrations and Italian universities in international research projects on integrated fire management, such as FIRE PARADOX ([25], [7]), ALPFFIRS ([84]) and PROTERINA-C ([70]). Italian PB experiences aimed at simultaneously achieve different management goals, such as fire hazard reduction and silvicultural prevention ([25], [46], [83], [6]), or habitat restoration and grazing management framed within programs for the regulation of pastoral uses of fire ([2], [26], [84], [19]). PB experiences were carried out in different vegetation types and EU priority habitats (Tab. 3 - DH 92/43/CEE). Moreover, most interventions were also used for firefighter and forestry operator training ([25], [46], [83], [4], [55]).
Tab. 3 - Prescribed burning experiences in Italy by land management goal and vegetation type.
Management goal | Vegetation type |
---|---|
Fire hazard reduction |
- Conifers: Pinus canariensis; P. halepensis; P. pinaster; P. pinea. - Broadleaves: Castanea sativa; Eucalyptus sp.; Quercus cerris. - Mediterranean shrubs (species: Cistus sp.; Spartium junceum). - Grasslands (dominant species: Brachypodium sp.; Molinia sp.). |
Forest management |
- Quercus cerris high forest. - Picea abies clearcut slash. |
Habitat restoration |
- European dry heaths with Calluna vulgaris (code HD: 4030, sub. 31.229) encroached by Populus tremula and Betula pendula. - Semi-natural dry grasslands and scrubland on calcareous substrates (Festuco-Brometalia - *important orchid sites) encroached by Spartium junceum. - Eastern sub-mediterranean dry grasslands (Scorzoneretalia villosae - cod. HD: 62A0). - Lowland hay meadows (Alopecurus pratensis, Sanguisorba officinalis - cod. HD: 6510). |
Grazing management |
- Grazed Quercus suber. - Grasslands (dominant species: Molinia arundinacea; Brachypodium spp.). |
Fire fighters training | All types |
Studies on fire hazard reduction and forest management
The most common goal of PB experiences in Italy is wildfire prevention ([7]). Operations were performed in even-aged plantations of Mediterranean pines (Tab. 3), e.g., Pinus canariensis, P. halepensis, P. pinaster, P. pinea ([25], [46], [83], [6]), but also in broadleaf forests, e.g., Eucalyptus sp., Quercus cerris ([20]), and in continental ([5]) and Mediterranean ([70]) grasslands and shrub communities.
PB in conifer plantations was carried out in winter, with low intensity fires (<150 kW m-1). The aim was to reduce fuel load and break fuel continuity in the litter layer, without damaging adult trees ([7]). The results were encouraging, both in terms of stand-scale hazard mitigation ([25], [46], [83], [6]), and of fire effects on soil and vegetation ([19], [69]).
A PB experiment was carried out in a fire-prone Pinus halepensis forest in Cilento e Vallo di Diano National Park. One year after burning, litter fuel load was 47% lower than the control ([6]), and 93% lower in the herbaceous layer dominated by Ampelodesmos mauritanicus (Poir.) Dur. & Schinz - one of the most flammable Mediterranean species ([37]). To evaluate the effectiveness of PB treatment in reducing fire hazard, Ascoli et al. ([6]) simulated potential wildfire behavior at the stand level in treated and untreated areas using PiroPinus, a decision support system for PB in Mediterranean pine forests ([32]). Moderate, high and extreme fire weather conditions were simulated by using the 70th, 90th, 97.5th percentiles of the fine dead fuel moisture distribution as estimated by PiroPinus (i.e., 11%, 9% and 8%, respectively). Under the 97.5th scenario, simulated headfire rate of spread, flame length and intensity in treated areas were respectively 25%, 69% and 88% lower than the control. The effect was attributed both to the reduction in surface fuel load, and to the breakup of vertical continuity among fuel strata ([6]). An analysis of fire effects on soil did not evidence changes in the microbial community and organic carbon content, except for short-term effects in the fermentation layer ([19], [69]). Similar results were observed after PB in a Pinus pinaster stand in the Cilento Park ([19]).
PB for managing firebreaks in herbaceous and shrub fuel beds was experimented in highly fire-prone areas, in order to evaluate its effectiveness in mitigating fire behavior at the stand ([5]) and landscape scale ([70]). Ascoli & Bovio ([4]) tested the effectiveness of prescribed burning in reducing fire hazard in heathland-grass fuels, one of the most flammable fuel types in northern Italy. They analyzed fire behavior in field fire experiments under moderate weather conditions during the winter high fire danger season. A comparison was made between areas treated with PB within 3 years, and control areas where time since fire was up to 14 years. Fireline intensity was significantly reduced in prescribed burnt vs. untreated areas of 74% and 80% for backfire and headfire, respectively. They showed that PB in heathland fuels is effective in reducing fire hazard at the stand level up to 3 years after treatment ([5], [4]). In Sardinia, PB was applied in 2011 to create a network of strategic fuel breaks to protect the city of Nuoro ([70]). Fuel breaks in grass fuels, for a length of 12.5 km, were realized before the beginning of the summer high fire danger season. The study showed an average 90% fuel load reduction. The analysis of the effectiveness of fuel breaks in mitigating fire risk at the landscape scale was carried out using the FARSITE fire growth model ([33]). It showed that fuel breaks performed well in mitigating simulated fire behavior under low to moderate fire weather conditions, but poorly under extreme weather ([70]). This study stressed the effectiveness of PB in maintaining strategic fuel breaks, which may ease the action of fire fighting operators and provide them with anchor points for tactical fire use.
Studies in grazing management and habitat conservation
While fire prevention is the most common goal of PB in Italy, it has often been integrated by other objectives of local interest, such as range management and habitat conservation ([7]). Most of the Italian experiences are in fact the result of collaboration between stakeholders with different interests and roles: (i) firefighting authorities (i.e., National Forest Service, Regional Forest Service, Civil Protection), whose interest is to prevent wildfires and train staff; (ii) private forest and range owners, who wish to improve their revenues and ensure the safety of their assets; (iii) local governments, responsible for land management and planning; (iv) Park authorities, that are mostly concerned with the conservation of specific habitats and landscapes; (v) researchers. In some Regions, action was taken to resolve conflicts between the use of pastoral fire and habitat conservation goals, such as in EU Natura 2000 sites ([2], [26], [84], [20]). In Piedmont, an experimental program for the conservation of Calluna vulgaris Hull. (cod. 4030, Habitat Directive 92/43/CEE) has been carried out since 2005 by combining PB and grazing treatments ([2]). Heathlands are a cultural landscape whose conservation, once helped by periodic pastoral fire, is now threatened by its irrational application ([11]). Upland heathlands originated in the early Middle Ages from deforestation by fire, and have been preserved thanks to continued mowing, grazing and periodic use of fire on small areas ([2]). Today, livestock density reached a minimum, and fire is being used during the period of maximum danger (i.e., in late winter), with a consequent increase in area burned ([11]). This fire regime is in part a consequence of fire bans and the loss of traditional knowledge ([3]). Shepherds ignite fires surreptitiously, when they are sure that the fire will self-sustain and spread, so as to be able to leave the scene. These uncontrolled fires burn under severe fire weather and spread over areas far greater than those necessary for pasture management. The combination of frequent fire and infrequent grazing causes the encroachment of fire-resilient tree species (e.g., aspen Populus tremula L.) at the expense of the heather ([3]).
PB and grazing treatments have been replicated on small blocks since 2005 in collaboration with local shepherds, with the aim of controlling invasive grass ([48]) and tree species ([9]), restore the heathland habitat, and establish prescriptions to regulate pastoral fire ([2]). After 7 years of monitoring, results were encouraging. Medium intensity fires (500-1500 kW m-1) caused high mortality of aspen stems. Yearly grazing allowed to control fire induced resprouts, and resulted in a tree basal area 72%, 80% and 86% lower than that in the fire-only, goat browsing-only and control treatments, respectively, allowing the heather to recover ([9]).
A similar program has been implemented since 2008 in the Cilento Park ([7]) for the restoration of pastures encroached by Spartium junceum L., and the conservation of semi-natural dry grasslands (cod. 6210 - Festuco-Brometalia *important orchid site, HD 92/43/CEE). Experimental burn sites have been chosen in agreement with local shepherds, who use fire regularly in the area. Two hectares were treated in 2009 and 8 ha in 2011 (Fig. 5). Assessment of the effect of PB on soil, flora ([20]) and fauna ([67]) followed. Catalanotti et al. ([20]) used thermocouple measurements (K-Type) to analyze the relationships between flame temperature residence times and fire effects in the soil. Because of high temperature on litter surface (850°C), with a mean residence time above 100°C of 428 seconds, an alteration in microbial biomass and activity was found in the fermentation layer and, temporarily, also in the soil beneath. The author conclude her analysis stressing the importance of adequate control of fuel moisture levels when applying intense fire treatments to minimize heat transfer to soil and the need for fire use prescriptions targeted to this habitat ([20]).
Fig. 5 - Prescribed burning in encroaching Spartium junceum shrubland in the Cilento and Vallo di Diano Park. The prescribed burning was carried out in February 2011 at Sella del Corticato. The burn covered an are of 8 ha with the objective to prevent pastoral fire use, open encroached areas for grazing and re-establish grassland habitats.
Valese et al. ([84]) analyzed fire behavior during PB in pastures subjected to recurrent pastoral fires in the southeastern Alps. Burn conditions were more conservative than in Catalanotti et al. ([20]): soil temperatures were between 0-5°C and duff moisture content was 187% (dry weight basis). Fire temperatures were measured using thermocouples (K-Type), positioned at the soil surface and within the organic soil. Maximum flame temperature at the soil surface was 620°C and residence time above 100°C was 45 seconds. Maximum temperature in the soil was 19.5°C, and mean residence time between 5 and 20°C was 171 ± 60 seconds. These results suggest that heat transfer to the soil can be strongly mitigated by suitable duff moisture prescriptions ([84]).
A prominent example of a participatory program to resolve pastoral fire use conflicts has been implemented in Sardinia ([26]), as documented on film by Ribet ([66]). In Sardinia, fire is still an important cultural practice, and is considered an effective tool for the disposal of agro-forestry residues, stubble, and for rangeland improvement. The Regional Forestry Service is gradually implementing an integrated fire management approach ([27]) to support shepherds, include pastoral fire within a broader fire management strategy, and, at the same time, train the operators in the expert use of fire ([26], [70]).
Experiences in firefighter training
All PB experiences in Italy have provided opportunities for training firefighting personnel. Courses were held between 2007 and 2012 in Basilicata ([46]), Tuscany ([83]), Piedmont ([4]), Campania ([7]) and Liguria ([55]). In Sardinia, an institutional team was licensed in 2008 for the use of fire (Mastros de Fogu), for both prescribed burning and fire suppression ([26]). Courses were held by both Italian and foreign professionals, such as Portuguese GIFF (⇒ http:// www.giff.pt/website/) for the training in Campania ([7]) or the French Office National des Forêts in Liguria ([55] - Fig. 6). Recently, selected operators from firefighting services of Tuscany and Lombardy have attended training courses on PB, in collaboration with the Catalan GRAF, and the latter practiced the technique during a study tour in Cataluña.
Fig. 6 - Prescribed burning training in Liguria. The training course started in October 2011 ended with a field training in March 2012 within a collaboration between the Corpo Forestale dello Stato (Imperia Province), the Liguria Region and the Office National de Forêt of Corse. (Photo: G. Castiglione, CFS - Imperia).
Despite initial skepticism on the technique, as we previously summarized ([45]), awareness and interest of professional operators on the subject is increasing. In this process, a key role was played by training visits of Italian personnel to France, Portugal and Spain ([7]).
Classroom and field training sessions for PB planning, application and monitoring provided operators with new proficiencies and analytical skills: (i) a greater understanding of the principles of fire ecology in forest ecosystems and of fuel management for fire prevention; (ii) the ability to analyze and anticipate the behavior of the flame front as a function of vegetation, meteorological and topographical variables; (iii) the ability to use models (e.g., fire behavior fuel models) and decision support tools (e.g., fire danger ratings, fire behavior simulators); (iv) practical procedures for flame front control, workers’ safety and post-fire restoration. These results confirm the high potential of PB in Italy for the training of firefighting personnel ([16]) and professional positions such as the Director of fire control operations and the Fire Analyst ([26], [83]), which are widely recognized and developed in European ([56]) and extra-European countries with highly specialized fire management systems ([42]).
Challenges of prescribed burning in Italy
This review shows that prescribed fire could be applied in Italy for multiple and integrated objectives: (i) managing fuel breaks in fire-prone areas with herbaceous and shrub fuel beds; (ii) periodically reducing litter fuels in mature conifer forests exposed to recurrent fires; (iii) supporting pastoral activities and range management; (iv) promoting conservation of habitats and cultural landscapes where periodical fire is an important ecological factor; (v) firefighters training. The integrated and multidisciplinary approach adopted in most of the described experiences has allowed overcoming some issues that had been identified in the past ([16], [79], [45]). The following outcomes have resulted: (i) participatory processes in sharing PB objectives, methods and results; (ii) knowledge transfer between stakeholders; (iii) better definition of authorization protocols, technical procedures, and attributed responsibilities; (iv) recovery of traditional knowledge ([7]).
Similar results have been obtained from the established practice of PB in Europe ([77]), where problems and solutions were similar to those illustrated for Italy ([30], [10], [24], [43], [44], [88]). However, as noticed by several authors ([80], [16], [79], [45]), PB experiences from foreign countries must be weighted on the existing differences in geographic, environmental and socio-economic conditions. Applying PB in Italy requires a thorough knowledge transfer and a body of research based on repeatable experiments, carried out at an adequate spatial and temporal scale, and adopting an adaptive approach ([2]).
Open research questions still remain about where, when and how PB should be planned and used. In particular, they concern: (i) PB effectiveness for fire hazard reduction; (ii) prescribed fire regimes which maximize ecosystems services while reducing ecological concerns; (iii) technical prescriptions for burn objective and environment of application; (iv) smoke diffusion models in the RUI and in areas with a complex topography; (v) the overall balance of greenhouse gas emissions, taking into account the mitigation of wildfires; (vi) the costs of PB in comparison to other established fuel management techniques; (vii) the need for communication and citizen awareness on the issues of fire prevention and ecology ([7]).
As regard fire hazard reduction, the PB effectiveness in abating the overall burnt area (i.e., leverage) is proportional to the wildfire area extent of a specific territory ([60]). When wildfire incidence on the overall vegetation area is low, most of the treated areas are not encountered by a fire and so cannot be effective. Consequently, the low fire incidence in Italy (e.g., 1.29% - Tab. 2) seems to not justify a PB strategy at the national level. However, fire management is set by Regional administrations ([14]) which identify local priority areas where wildfire incidence is high and where PB, implemented in a strategic spatial design ([60]), could be effective. Moreover, the landscape fragmentation and relatively less severe fire weather which characterize the Italian territory may increase PB effectiveness, as reported for other southern European countries ([89]). Deepening these issues could improve PB planning for fire hazard reduction in highly fire-prone areas of Italy.
Research on the effects of PB regimes in specific habitats and forest ecosystems could be viewed as an opportunity for developing new research ideas in forest ecology. The Italian landscape has changed dramatically in the recent decades. Abandonment of agricultural and forest activities in mountain areas has been affecting biodiversity ([78]) and fire risk at the landscape scale ([39]). Several authors stressed the importance of increasing landscape heterogeneity also by means of prescribed fire (e.g., [58]). Given the important role that fire has played in fostering biodiversity in Italian ecosystems ([76], [26], [22], [29]), there is much research potential on the effectiveness of PB for biodiversity conservation. Ascoli et al. ([7]) identified several EU Natura 2000 habitats (code Habitat Directive: 2240, 2270, 4030, 6220, 62A0, 6510, 9540), in addition to marshlands dominated by Carex spp. and Phragmites australis (Cav.) Trin., in which appropriate burning prescriptions integrated within management plans could help establishing disturbance regimes compatible with the conservation of biological values. Research is increasingly demonstrating the importance of fire for natural regeneration in Italian forests, not only dominated by early-serial conifers, e.g., Larix decidua, Pinus laricio, P. halepensis, P. pinaster, P. pinea, P. sylvestris ([71], [59]), but also by shade tolerant species, which are usually believed to display less specific fire-adaptive traits. For example, single fire events preceding mast years could be one of the most effective regeneration pathways in old-growth beech ([86], [8], [50]). Further analysis could lead to reconsider the use of fire in forests, especially where landscape and habitat values are the ecosystem services at stake.
Preliminarily to introducing PB in Italy, however, appropriate regulations must be issued at the regional level, which clarify: (i) administrative responsibilities; (ii) authorization procedures of PB projects, homogeneous at the national level, quick and flexible in order to exploit the narrow window suitable for operations; (iii) safety measures; (iv) specialists required. Bovio & Ascoli ([14]) emphasized the need to regulate PB at the national level by updating the legislation on forests, parks and wildfire, and possibly framing it in a European directive on the use of fire ([57]). Finally, as is customary in other countries, it is necessary to design a professionals certification system for the planning, use and analysis of PB, that incorporate aspects of ecology and forest management, fire behavior prediction, and fire control operations ([25], [83], [14]).
There are many issues to address in order to integrate PB in land management plans in Italy. This work provides a synthetic framework on this subject of international interest. We anticipate it to have positive effects on future research and application of prescribed burning in Italy, and contribute to the current debate on fire prevention vs. fire control policies and investments ([13], [27]). The increasing costs of fire control and the paucity of public finances in Italy should bring under attention the opportunity for prescribed burning as one of the available strategies in integrated fire management ([58], [77]), in order to face fire issues in a changing society, landscape and climate.
Acknowledgments
The work was financed by the project PRIN 2009 “in_FLAMING: Developing innovative models and techniques for integrated fuel management for fire prevention in Mediterranean and temperate forests” (coordinator: P. Corona) funded by the Italian Ministry for Education, University and Research. We are grateful to Giorgio Vacchiano for language revision and comments.
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Ascoli D, Bovio G (2013). Prescribed burning in Italy: issues, advances and challenges. iForest 6: 79-89. - doi: 10.3832/ifor0803-006
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Marco Borghetti
Paper history
Received: Sep 29, 2012
Accepted: Nov 20, 2012
First online: Feb 07, 2013
Publication Date: Apr 02, 2013
Publication Time: 2.63 months
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© SISEF - The Italian Society of Silviculture and Forest Ecology 2013
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This article is distributed under the terms of the Creative Commons Attribution-Non Commercial 4.0 International (https://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
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